1. Field of the Invention
The present invention relates to a method for manufacturing a magnetic head for perpendicular magnetic recording/reproducing.
2. Description of the Related Art
A perpendicular magnetic recording/reproducing process is less affected by thermal fluctuations even if the areal recording density is increased, as compared with an in-plane magnetic recording/reproducing process which has been conventionally used in wide applications. For this reason, the perpendicular magnetic recording/reproducing process is drawing attention in recent years as a technology which can satisfy the demand for an increased areal recording density in magnetic recording/reproducing apparatuses such as hard disk drives.
One problem of this perpendicular magnetic recording/reproducing process is that a magnetization pattern, which essentially should be recorded straight with respect to the track width direction (radial direction of the magnetic recording medium) of a magnetic recording medium, is recorded curved with respect to the track width direction. This problem will be described below in brief, although it is described in Japanese Patent Laid-open Publication No. 2002-279606 (hereinafter called Patent Document 1).
Perpendicular magnetic recording/reproducing apparatuses often employ a magnetic head in a monopole type. When a magnetic head in this type is employed, contour lines in the magnetic writing field generated from the main magnetic pole are distributed concentrically, with the maximum strength appearing at the center of the main magnetic pole.
When a magnetic head in a monopole type is employed, the magnetization pattern recorded on a magnetic recording medium mainly depends on the magnetic writing field on the trailing edge of the main magnetic pole, i.e., downstream side in a direction in which the magnetic recording medium is rotated. Since the contour lines in the magnetic writing field generated from the main magnetic pole are distributed concentrically with the maximum strength appearing at the center of the main magnetic pole, as mentioned above, the contours in the magnetic writing field are curved with respect to the track width direction on the trailing edge that is spaced from the center of the main magnetic pole. Accordingly, the magnetization pattern recorded on the magnetic recording medium is curved with respect to the track width direction.
This phenomenon of magnetization pattern curving with respect to the track width direction may cause a lot of undesirable results, such as limiting an increase in the linear recording density and the deterioration in the reproduced signals.
According to the invention described in Patent Document 1, the main magnetic pole has an arcuate recess on the trailing edge, in order to change and correct the contour lines in the magnetic writing field generated from the main magnetic pole.
In the paragraphs 0008 to 0010 in the above-mentioned Patent Document 1, a process is described for forming an arcuate recess in the main magnetic pole on the trailing edge, using ion milling, RIE (Reactive Ion Etching), and CMP (Chemical Mechanical Polishing) for that purpose.
However, no description is made regarding the steps and the conditions for ion milling, RIE, or CMP in Patent Document 1. A description is given in the paragraph 0009 that since the central portion of the main magnetic pole differs in composition and crystallinity from the other portion, and is less resistive to polishing, an arcuate recess can be naturally formed in the main magnetic pole on the trailing edge by polishing rather strongly by CMP. However, using such a process would make it considerably more difficult to enhance controllability and reproducibility of the arcuate recess as well as to enhance uniformity within a wafer.